Number wheel for counters

ABSTRACT

A number wheel has a first circular portion provided with a center hub having an axis, and with a plurality of passages which are spaced from and asymmetrically distributed about the hub and each of which has an axis paralleling the axis of the hub. A discrete second circular portion has a center portion received in the hub and centers the second circular portion with reference to the first circular portion adjacent one axial end of the latter, and a plurality of projections each of which is frictionally received in one of the passages.

United States Patent 1191 Muller 1451 Nov. 11, 1975 1 NUMBER WHEEL FOR COUNTERS [75] Inventor: Helmuth Muller, St. Georgen,

Germany [73] Assignee: Kienzle Apparate GmbH, Villingen,

Germany [22] Filed: Dec. 28, 1973 21 Appl. No.: 429,217

[30] Foreign Application Priority Data Jan. 16. 1973 Germany 7301498 [52] US. Cl. 235/1 C; 235/117 R [51] Int. Cl. G06C 11/02 [58] Field of Search... 235/1 C, 115, 144 R, 144 M, 235/117 R, 117 A, 118

[56] References Cited UNITED STATES PATENTS 1.671.553 5/1928 Sheldrick 2115/] C 2.279.337' 4/1942 Niemann 235/1 C 2.813.679 ll/1957 Heston 235/117 R 3,138,323 6/1964 Yolin 235/1 C 3.380.654 4/1968 Williams 235/1 C X Primary E.\'aminerL. T. Hix Assistant E.\'aminerStan1ey J. Witkowski Attorney, Agem, or Firm-Michael S. Striker ABSTRACT A number wheel has a first circular portion provided with a center hub having an axis, and with a plurality of passages which are spaced from and asymmetrically distributed about the hub and each of which has an axis paralleling the axis of the hub. A discrete second circular portion has a center portion received in the hub and centers the second circular portion with reference to the first circular portion adjacent one axial end of the latter, and a plurality of projections each of which is frictionally received in one of the passages.

11 Claims, 6 Drawing Figures US. Patent N0v.'1 1,1975 sheetlo s 3,918,634

U.S. Pate nt Nov. 11, 1975 Sheet 2 of3 3,918,634

US. Patent Nov. 11, 1975 Sheet 3 of3 3,918,634

FIG. 2b

1 NUMBER WHEEL FOR COUNTERS BACKGROUND OF THE INVENTION The present invention relates generally to a number wheel for counters and the like, and more particularly to an improved number wheel of this type and to a method of making it.

Number wheels of the type here in question are used in counters provided with a plurality of number wheels, so that the counter can count in tens or hundreds, or higher numbers. Each of the number wheels represents a decade, that is ten numerals, and when the numerals which are provided on a respective wheel have been counted, the wheel switches over to the next-following wheel while itself returning to a zero-setting position. It is already known in such constructions that each of the number wheels is provided with a projecting trip cam which, as the number wheel moves toward its own zerosetting position causes the next-following number wheel to be moved for a certain angular distance to thereby initiate the counting operation by this nextfollowing number wheel. Frequently, the zero-setting operation is obtained by having a zero-setting lever act upon a zero-setting cam track of the respective number wheel, causing the number wheel to be returned to zero-setting position.

All components of a number wheel, such as the annulus of gear teeth by which it is driven, the scalar marking of the wheel of the numbers, the zero-setting cam track, the trip cam and the like must be arranged in a precisely predetermined angular position relative to one another in the finished number wheel, in order to assure correct counting and also correct zero-setting indication. Moreover, the various components must be arranged as precisely coaxial with reference to one another during the installation, because otherwise malfunctions can occur in operation'of the counter.

A problem which has been encountered and which will already be evident from the foregoing remarks, is that on the one hand such number wheels must provide for great accuracy, but on the other hand they should, of course, be produced as inexpensively as possible. Attempts have been made to meet these two divergent requirements; for instance suggestions have been made for stamping and pressing a number wheel from sheet metal, and producing a gear provided with the necessary drive gear teeth separately from the number wheel, connecting the two components by welding or riveting in the desired relative angular orientation. However, it has been found that such an operation is nevertheless rather expensive, particularly because the stamping operation must be precise and various defer? mations must be stamped into the number wheel itself for bearings, the trip cam and the like. If all of these parts and components are to be produced with reasonable precision, it is necessary that the tools and tool materials be of high grade, and therefore expensive. Again, the connection of the number wheel with the drive gear is expensive and particularly if a riveting connection is established, great'care must be exercised in order to obtain the requisite accuracy. 7

ther approaches have also been proposed, again based upon the separate manufacture of various components of the number wheel, and their subsequent connection by welding, riveting or the like via a series of separate operating steps. This, also, is expensive and time and labor intensive.

Basically, therefore, the known number wheels from the prior art suffer from one or more disadvantages which can be characterized as difficulties in producing the components themselves, difficulties in connecting the components, expense in connecting the components, too many components requiring too many connecting steps and/or the possibility of undesired separation of the connected components.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to avoid the disadvantages of the prior art.

More particularly, it is an object of the invention to provide an improved number wheel for counters and the like which is not possessed of these disadvantages.

An additional object of the invention is to provide such an improved number wheel which has only a minimum number of components, and the components of which can be produced in a very simple manner and require no subsequent finishing operations.

An additionalobject of the invention is to provide such a number wheel which not only consists of a minimum number of-components, but wherein the components can be very readily and simply connected with one another, without requiring additional connecting elements and without requiring the exercise of particular care in such assembly.

Another object of the invention is to provide a method of making such a novel number wheel.

In keeping with the above objects, and with others which will become apparent hereafter, one feature of the invention resides in a number wheel for counters and the like which, briefly stated, comprises a first circular portion provided with a center hub having an axis, and with a plurality of passages which are spaced from and asymmetrically distributed about the hub and which each have an axis paralleling the axis of the hub. A discrete second circular portion is provided, having a center portion-received in the hub and centering the second circular portion with reference to the first circular portion adjacent one axial end of the latter, and a plurality ofprojections each of which is frictionally received in oneof the passages. The circular portions are thus prevented from relative axial and angular displacement and together constitute the novel number wheel.

It is currently preferred if one of the circular portions, for instance the first circular portion, is provided with an annulus of numerals and with a ring of gear teeth, whereas the other circular portion is provided with a zero-setting cam track, a mounting collar and a trip cam.

The hub and the center portion are advantageously both of tubular configuration and so dimensioned with reference to one another that when the two circular portions are connected, the hub and the center portion will be arranged coaxially with reference to one another. They should be as long as possible so that one can extend into the other over the maximum possible axial length, in order to provide a very reliable and play-free connection between them. Concentric with the hub and the center portion they are provided at the respective axial ends of the first and second circular portions which face away from one another, with nartogether with additional row journalling surfaces which serve for mounting of the number wheel.

The asymmetrically distributed passages and similarly the projections are spaced at different radial distances from the axis of the hub and based upon the height of their position with respect to the line of separation between the circular portions, and with respect to their number as a three point connection they determine the spacing and the plane-parallel position of the circular portions with reference to one another.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an axial section through a number wheel ac- DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing in detail, it will be seen that FIGS. 1 and 1a show the novel number wheel to be composed of two circular portions 1 and 2, each of which is of one piece. The circular portion 1 has an essentially cup-shaped part 3 which carries on its outer circumferential surface the numerals or the like (not shown since conventional). The transverse end wall 3a is provided with an axially projecting annulus 4 of gear teeth which is engaged in known (and not illustrated) manner by the drive means conventional in counters. At the same axial end as the wall 3a there is provided ajournal for the number wheel, in form of an inner circumferential surface 6 which is of relatively short axial extent.

Projectiong towards the left in FIG. 1 from the end wall 3a is a tubular hub 5 the center bore of which is larger than the diameter of the opening surrounded by the surface 6 and coaxial with this opening. The axial length of the hub 5 should be as great as possible within the limitations imposed by the overall dimensions of the portion 3. There is a short conical transition between the diameter of the opening bounded by surface 6 and the maximium diameter of the passage in the hub 5. The hub Sis, of course, concentric with the outer circumferential wall of the portion 3. Except for the portion having the surface 6, the hub 5 projects freely within the hollow circular portion 1 and this substantially improves operating characteristics of the novel number wheel because it permits a smaller bearing play on the shaft (not shown) while at the same time holding the size of the surface 6 where friction occurs with the shaft to the minimum.

Also within the hollow interior of the portion 1 there is provided a number of asymmetrically arranged portions 7 having passages which extend in parallelism with the axis of the hub 5, as is clearly shown in FIGS. 1 and 2b. The portions 7 each have a cylindrical bore at the end which faces towards the circular portion 2, and this bore 7c merges via a conically convergent bore portion 7a into an enlarged-diameter bore portion 7b. There is a sharp edge at the junction of the bore portions 7a and 7b. The enlarged-diameter bore portion 7b permits the head 13/l 13/2 or 13/3 of the projections of the circular portion 2 (which will be discussed subsequently) to change its configuration, for instance its diameter, once it has passed beyond the sharp edge at the junction of the bore portions 7a and 7b.

In the illustrated embodiment, the portions 7 are asymmetrically arranged in that they are spaced at different radial distances from the axis of the hub 5. The height of the portions 7, that is the dimension thereof of the direction towards the line of separation between the circular portions 1 and 2 when the latter are assembled, and the arrangement of preferably three of the portions 7 distributed over the circumference of the number wheel, provide for a stable three point contact between the portions 1 and 2, and the portions 7 constitute contact portions which determine the spacing and plane-parallel and angularly correct relative position of the portions 1 and 2 with reference to one another.

Parenthetically, it is mentioned that the portions 7 could all have the same radial distance from the axis of the hub 5, in which case they could be arranged at different angular spacing from one another, rather then being equiangularly spaced about the axis of the hub 5. In this modification, also, the advantages of the present invention will be obtained.

Coming now to the circular portion 2, it will be seen that this is formed with a zero-setting cam track 10, a mounting collar 9 and a projecting trip cam 8. The portion 2 is further provided with projection 13/1, 13/2 and 13/3. It has a transverse wall 2a from which the collar 9 projects in one axial direction while the portion formed with the zero-setting cam track 10 projects in the opposite axial direction (towards the right inFIG. 1). Also projecting from the transverse wall 2a is a center portion 11 which is configurated as a tubular portion and is received over a part of its axial length in mating relationship within the interior of the hub 5. The extent to which the portions 5 and 11 are interengaged with one another in axial direction should be as great as possible, as mentioned earlier, in order to assure proper and stable play-free centering of the two portions 1 and 2 with reference to one another. The portion 11 is provided with an inner circumferential journalling surface 12 similar to the journalling surface 6 and also having a relatively short axial extension in order to reduce friction with the mounting shaft. The diameter of the opening surrounded by the. journalling surface 12 is substantially smaller than the diameter of the remainder of the passage in the portion 11. The concentric arrangement of the portions 7 and l3/l, l3/2 and 13/3 with reference to the portions 5 and 11 can be produced readily and without any difficulty during the manufacture of the portions 1 and 2, and narrow tolerances can be maintained without problems. This is an advantage not only in manufacturing terms, but also in terms of improved smoothness of rotation.

Projecting towards the right in FIG. 1 from the transverse wall 2a are the projections 13/1, l3/2 and 13/3 each of which is received in one of the portions 7, as shown. At the base of each of the projections 13 there is provided a collar 16 which is produced by forming an annular groove or cutout 14 at each base, surrounding the base. The collars 16 serve as abutments with respect to the associated portions 7, and the grooves 14 assure that the projections 13/l,l3/2 and 13/3 can flex to a slight extent so that they can'be readily inserted into the passages of the respective portions 7 even though a slight tolerance variation should have occurred during manufacture. This is clearly shown, for instance, in FIG. 2a, from which Figure it is also seen that the grooves 14 are formed on the side facing the circular portion LHowever, although this arrangement provides advantages in terms of avoiding a coincidence of shear effects and kerf effects at the base of the re spective projections l3/l 13/2 and l3/3, it is also con ceivable to have grooves 14 of lesser depth extend into the wall 2a from both axial sides thereof, or to provide similar grooves in the portions 7, surrounding the bore portion 7c therein.

It is advantageous if, as shown in FIGS. 2a and 2c, the respective projection 13/1, 13/2 and 13/3 is provided with fluting or axially extending .grooves 13a over at least that part of it which will be received in the bore portions 70 and 7a of the respective portion 7, so that the exterior cross-sectional appearance resembles a star or the like. The free end of the respective projection 13/ 1, 13/2 and 13/3 may advantageously be provided with a conically configurated bevel 13b to facilitate its insertion into the bore portion 70 and its passage through the bore portion 7a.

As FIG. 1 shows, the projections 13/1, 13/2 and 13/3 may be provided inwardly of their free ends and inwardly of the bevel 13b with a circumferential groove (not numbered in FIG. 1) in which the sharp'edge bounding the bore portion 7a at the junction thereof with the bore portion 7b can become lodged (see the groove 15 in FIG. 3) to prevent undesired withdrawal of the projections 13/1, 13/2 and 13/3. For this purpose, either the projections 13/1, 13/2 and 13/3, the portions 7 or both must be somewhat resiliently deformable to permit the insertion of the projections 13/1, l3/2 and 13/3 through the bore portion 7a and the snap-action entry of the sharp edge into the respective groove 15.

The portions 1 and 2 can be readily produced, for instance by injection molding from a synthetic plastic material, and when they have been so molded they do not require any subsequent finishing operations. Suitable plastic materials for this purpose are well known, for instance nylon or the like, and injection-molding techniques for molding each of the portions 1 and 2 of one piece are well known in the art and require no detailed discussion.

Moreover, the assembly of the portions 1 and 2 with one another requires neither tools nor auxiliary elements such as jigs or the like, and no connecting components are needed, nor is welding or connecting of other type required, except for a positioning of the portion 2 adjacent the lefthand axial end of the portion 1 (in FIG. 2) and a pressingtogether of the two portions so that the portions 13/1, 13/2 and 13/3 will snap into the portions 7. This assembly is both quick and simple, and can be carried out by semi-skilled or even unskilled personnel. During this snap-action connection, the sharp edge at the juncture of the bore portions 7a and 7!) will enter into the groove 15 and prevent undesired withdrawal of the respective projection 13/l, l3/2 and 13/3. It should be understood, however, that the material of the projections 13/1, l3/2 and 13/3 can also be sufficiently yieldable to eliminate a need for providing the groove 15. In that case, the sharp edge itself will deform the material of the respective projection 13/1, 13/2 and 13/3 to such an extent as to create its own groove corresponding to the groove 15. In either case, however, a reliable connection betweeen the portions 1 and 2 will be established which can be reversed (in a sense separating the portions 1 and 2 from one another) only by destroying the material of the portions 7 and/or projections l3/l, l3/2 and 13/3 where they interengage.

By appropriate arrangement of the projections 13/1, l3/2 and 13/3 and the portions 7, a certain relationship between the zerosetting cam track 10, the trip cam 8, the collar 9 on the one hand, and the numerals on the wall portion 3 and the gear teeth 4 on the other hand, can be established without requiring any additional means or particular attention on the part of the assembler. Moreover, each feature of each of the portions 1, 2 can be produced in one and the same operation, and each portion 1 or 2 can be produced of one piece without requiring particularly complicated molds for the production.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.

While the invention has been illustrated and described as embodied in a number wheel for counters and the like, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should andare intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. A number wheel for counters composed of a first circular portion provided with a center hub having an axis, and with a plurality of passages which are spaced from and asymmetrically distributed about said hub and which each have an axis paralleling the axis of said hub; and a discrete second circular portion having a center portion received in said hub and centering said second circular portion with reference to said first circular portion adjacent one axial end of the latter, and a plurality of projections each of which is frictionally received in one of said passages, said circular portions thus being prevented from relative axial and angular displacement and together constituting said number wheel.

2. A number wheel as defined in claim 1, wherein said first portion is provided with a circumferentially extending part having a series of numerals thereon, and

i with a ring of gear teeth: and wherein said second portion includes a circumferentially extending zero-setting cam track, a projecting trip cam and an axially projecting collar.

3. A number wheel as defined in claim I, wherein said hub and said center portion are configurated as respective tubular portions of differential length, said center portion being coaxially received in said hub.

4. A number wheel as defined in claim 3, wherein each of said tubular portions has an end portion which is spaced from the respectively other circular portion; and wherein each of said end portions is provided with an inner circumferential journalling surface.

5. A number wheel as defined in claim 1, wherein different ones of said passages are spaced by different radial distances from said axis of said hub.

6. A number wheel as defined in claim I, wherein there are three of said passages.

7. A number wheel as defined in claim 1, wherein said passages each have one open end facing toward said second circular portion, and an other open end facing away from said second circular portion, and wherein the diameter of said passages converges in the region of and in the direction towards the respective other open end, the respective other open end being bounded by a sharp edge.

8. A number wheel as defined in claim 7, wherein each of said projections has an end portion formed with a circumferentially extending outer groove in which said sharp edge of one of said passages is received.

".9. A number wheel as defined in claim 7, wherein said second circular portion has an axial end facing said first circular portion and from which said center porsaid passages. 

1. A number wheel for counters composed of a first circular portion provided with a center hub having an axis, and with a plurality of passages which are spaced from and asymmetrically distributed about said hub and which each have an axis paralleling the axis of said hub; and a discrete second circular portion having a center portion received in said hub and centering said second circular portion with reference to said first circular portion adjacent one axial end of the latter, and a plurality of projections each of which is frictionally received in one of said passages, said circular portions thus being prevented from relative axial and angular displacement and together constituting said number wheel.
 2. A number wheel as defined in claim 1, wherein said first portion is provided with a circumferentially extending part having a series of numerals thereon, and with a ring of gear teeth; and wherein said second portion includes a circumferentially extending zero-setting cam track, a projecting trip cam and an axially projecting collar.
 3. A number wheel as defined in claim 1, wherein said hub and said center portion are configurated as respective tubular portions of differential length, said center portion being coaxially received in said hub.
 4. A number wheel as defined in claim 3, wherein each of said tubular portions has an end portion which is spaced from the respectively other circular portion; and wherein each of said end portions is provided with an inner circumferential journalling surface.
 5. A number wheel as defined in claim 1, wherein different ones of said passages are spaced by different radial distances from said axis of said hub.
 6. A number wheel as defined in claim 1, wherein there are three of said passages.
 7. A number wheel as defined in claim 1, wherein said passages each have one open end facing toward said second circular portion, and an other open end facing away from said second circular portion, and wherein the diameter of said passages converges in the region of and in the direction towards the respective other open end, the respective other open end being bounded by a sharp edge.
 8. A number wheel as defined in claim 7, wherein each of said projections has an end portion formed with a circumferentially extending outer groove in which said sharp edge of one of said passages is received.
 9. A number wheel as defined in claim 7, wherein said second circular portion has an axial end facing said first circular portion and from which said center portion and said projections extend; and wherein said axial end of said second circular portion is provided with circular grooves each surrounding a base of a respective one of said projections so as to permit resilient deflection of the respective projection in transverse direction.
 10. A number wheel as defined in claim 7, wherein said projections are of star-shaped outer contour.
 11. A number wheel as defined in claim 10, wherein said projections each have an end portion formed with a conical bevel for facilitating its insertion into one of said passages. 